OBCP V4版本第二章培训材料闪回查询部分调整建议

[王现岗]

按照MySQL模式的示例执行输入时间后，提示时间戳非法，后查询文档，文档使用的是time_to_usec()的函数，执行没有问题。两个函数对于相同的时间转换后的值是不一样的。

[甯空]

mysql> select * from account;
+------------+-------+----------+---------------------+---------------------+
| account_id | name  | balance  | gmt_create          | gmt_modified        |
+------------+-------+----------+---------------------+---------------------+
|          1 | Allan | 10000.00 | 2025-03-10 17:07:50 | 2025-03-10 17:07:50 |
|          2 | Jack  | 20000.00 | 2025-03-10 17:07:50 | 2025-03-10 17:07:50 |
|          3 | John  | 10000.00 | 2025-03-10 17:07:50 | 2025-03-10 17:07:50 |
+------------+-------+----------+---------------------+---------------------+
3 rows in set (0.08 sec)

mysql> select * from account as of snapshot timestamp_to_scn('2025-03-16 14:52:00');
+------------+-------+----------+---------------------+---------------------+
| account_id | name  | balance  | gmt_create          | gmt_modified        |
+------------+-------+----------+---------------------+---------------------+
|          2 | Jack  | 20000.00 | 2025-03-10 17:07:50 | 2025-03-10 17:07:50 |
|          3 | John  | 10000.00 | 2025-03-10 17:07:50 | 2025-03-10 17:07:50 |
|          4 | Bart  | 10000.00 | 2025-03-10 17:07:50 | 2025-03-10 17:07:50 |
|          1 | Allan | 10000.00 | 2025-03-10 17:07:50 | 2025-03-10 17:07:50 |
+------------+-------+----------+---------------------+---------------------+
4 rows in set (0.01 sec)


mysql> select * from account as of snapshot time_to_usec('2025-03-16 14:52:00') * 1000;
+------------+-------+----------+---------------------+---------------------+
| account_id | name  | balance  | gmt_create          | gmt_modified        |
+------------+-------+----------+---------------------+---------------------+
|          1 | Allan | 10000.00 | 2025-03-10 17:07:50 | 2025-03-10 17:07:50 |
|          2 | Jack  | 20000.00 | 2025-03-10 17:07:50 | 2025-03-10 17:07:50 |
|          3 | John  | 10000.00 | 2025-03-10 17:07:50 | 2025-03-10 17:07:50 |
|          4 | Bart  | 10000.00 | 2025-03-10 17:07:50 | 2025-03-10 17:07:50 |
+------------+-------+----------+---------------------+---------------------+
4 rows in set (0.01 sec)

mysql>
mysql> select time_to_usec('2025-03-16 14:52:00') * 1000, timestamp_to_scn('2025-03-16 14:52:00');
+--------------------------------------------+-----------------------------------------+
| time_to_usec('2025-03-16 14:52:00') * 1000 | timestamp_to_scn('2025-03-16 14:52:00') |
+--------------------------------------------+-----------------------------------------+
|                        1742107920000000000 |                     1742107920000000000 |
+--------------------------------------------+-----------------------------------------+
1 row in set (0.00 sec)

mysql>

同学我试了下是一样的，5.7.25-OceanBase_CE-v4.3.4.0

[王现岗]

老师 我用的是4.3.5社区版
我的服务器时间比当前时间慢一点，慢了差不多15个小时，是和这个有关系吗？

[菜鸟收割机]

有吧